Well, my stint in *buntu is over, and it ends with an award to openSUSE: this is the first Linux distro I've returned to.
Kubuntu is nice, and I'm happy that I've tried it out, but it's not for me. It's nice enough if you want a simple desktop system, and APT rocks (especially with the aptitude front-end). But it's just not as good as openSUSE, sorry.
Quick note:- I use KDE nearly all the time. But sometimes I have occasion for a minimal desktop (e.g. when I plan to use just one, heavy program like FlightGear and need basically not much more than a window manager and X itself). So an alternate "light" desktop session type is nice to have.
Yes, I've joined the ubuntu train, and I'm travelling in the Kubuntu car (the caboose?). This will be, what, my fifth (or sixth if you count Knoppix, but I never put that on my hard drive) Linux distro since trying out RedHat 5.2 back in 1999. Previous to this I was using openSUSE 10.2 which is not a bad distro either and I always had my eye on SuSE. So, why yet another distro change?